1. Field of the Invention
The present invention relates to optical accessories, and more particularly, to an optical accessory for coupling to the output end of a optical scope to extend its capabilities.
2. Discussion of the Related Art
In the field of optics, there are numerous types of optical devices available. Additional equipment is required to permit the optical devices to be used in a low level light environment. An example of such equipment is a light or image intensifier.
The prior art includes many attempts to combine optical devices and image intensifying equipment, all suffering from significant disadvantages. One example is U.S. Pat. No. 4,822,994, ("Johnson"). Johnson discloses a small arms sight assembly which enables a firearm such as a revolver or rifle to be employed for both daytime and nighttime use. During daytime use, a first section of the scope, with an objective lens, is coupled to a second section, with an eyepiece, by a flange. However, for night use, the two sections are separated, an image intensifier is inserted between them, and the three parts are connected together by flanges. The procedure to convert the firearm from daytime use to nighttime use is complex and time consuming. Further, the three components are compatible for use only with each other.
Another example is U.S. Pat. No. 5,444,507, ("Palmer"). Palmer discloses a device for coupling a night vision device to a video camera recorder. The night vision device, a video camera recorder, and a stabilizing bracket are firmly secured to a mounting plate via screws. Attaching the night vision device to the camera recorder is time consuming and cumbersome since several parts need to be attached to the mounting plate.
Another example is a weaponsight sold by ITT as the F7200/F7201 ITT Modular Day/Night Weaponsight. This weaponsight system requires a user to interchange a day eyepiece assembly with a night eyepiece assembly in order to use the weaponsight at night. The night eyepiece assembly includes an image intensifier. The conversion of the weapon to nighttime use is time consuming because the day eyepiece must be removed before the night eyepiece is mounted. The same problem is true when the weapon is converted to daytime use. Furthermore, the night eyepiece cannot be used for any other purpose (e.g., it cannot be used as a night vision monocular).
Another problem in the prior art is that some mounting arrangements of the night use equipment requires the separation of the optic parts of an optical device. Since the optic parts are typically maintained in a controlled atmosphere within a housing, each separation affects the reliability and operation of the optic parts.
Another problem in the prior art is the inability to easily and quickly retrofit the night use equipment to an existing optical device if the known devices are custom configured for interoperability. Further, the night use equipment is for a single purpose, providing only for night vision and not for other functions such as thermal imaging or video imaging.
Therefore, there is a need in the art for a device that is easily and quickly mounted to an existing optical device to convert it for night use or otherwise extend its capabilities. Also, there is a need for an apparatus that converts an optical device for night use without significantly altering the device. Finally, there is a need for equipment that provides ready change between functions such as night vision, thermal imaging, and video imaging.